Can I do a border run to Myanmar after my student visa to extend my stay in Thailand?

Hi mates. Who knows if I could do a border-run to Myanmar after the student's visa? I was planning to leave Thailand but, recently changed my mind and would like to stand here another 30 days. For now, I've got a plan to go to Myanmar for Green Bus just to get a stamp. During the 2018 year, I haven't left Thailand. My citizenship allows me to have a 30-days at arrival and I already have a back tickets to my motherland on 1 of February. I've heard that Thai border-officers could make a stamp 7-14 or 30 days on their own, it that true? Thanks in advance for an answer